I ran my first IRC-based RPG this weekend, and it went surprisingly well. I didn't give myself any time to prepare, and just for kicks, decided that I wasn't going to go ahead with the plot (well, "plot") until I was able to get the whole party together. On top of that, as longpig's laptop is the only PC working in the house, I was typing for her as well as my NPCs.
I managed to keep the action rolling, manage everything and even keep up a pretty good atmosphere (it helps when the player's can't see me falling out of my chair laughing while I'm building tension, and the OOC channel is worth its bytes in gold!)
I was also worried that the party dynamics wouldn't translate well to text, and yet they did, perfectly (kudos to humourcide for a perfectly executed "Where's Waldo?" and to auntielil32 for yelling "HELP! ALIIIICE!" at the most tense, sneaky moment possible!)
I'm also told that there's a big lack of in-person RPGs among the Montreal crowd at the moment, so I'm thinking that I'll do a two-month (ish) rotation with my games. I'll run Planescape for 3 sessions (one every other week, alternating with curtana's excellent Diabolotin game) and then for the fourth session, I'll run a living-room game, probably the history-based game that I trialled in Aberystwyth, which some of my Aber players will remember.